自定义UICollectionCell的nil标签

Question

编辑：似乎与this相同的问题 我使用自定义布局和单元格进行了集合视图，但是我的单元格的位置有点偏离所以我决定对它们进行编号以便我可以更轻松地调试它。我跟着这个家伙的answer用标签给我的单元编号。不知何故，myLabel为零，导致我的应用程序崩溃。

我相信我已经正确连接了这些插座，但也许有人可以提供一个列表供我查看我是否做错了。

的ViewController

import UIKit

class ViewController: UIViewController, UICollectionViewDataSource, UICollectionViewDelegate {

  @IBOutlet var gridView: UICollectionView!

  private let reuseIdentifier = "DesignCell"
  private let numberOfSections = 1
  private let numberOfCircles = 48

  override func viewDidLoad() {
    super.viewDidLoad()
    self.gridView.registerClass(MyCell.self, forCellWithReuseIdentifier: reuseIdentifier)
  }

  func numberOfSectionsInCollectionView(collectionView: UICollectionView) -> Int {
    return numberOfSections
  }

  func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
    return numberOfCircles
  }

  func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {

    let cell = collectionView.dequeueReusableCellWithReuseIdentifier(reuseIdentifier, forIndexPath: indexPath) as! MyCell

    cell.myLabel.text = String(indexPath.item) // myLabel is nil and causes a crash
    return cell
  }

  override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
  }

}

GridLayout（我的自定义布局）

import UIKit
import Darwin

class GridLayout: UICollectionViewLayout {

  private let numberOfColumns = 12
  private let numberOfRows = 4

  private var cache = [UICollectionViewLayoutAttributes]()
  private var contentHeight: CGFloat = 0
  private var contentWidth: CGFloat {
    let insets = collectionView!.contentInset
    return CGRectGetWidth(collectionView!.bounds) - insets.left - insets.right
  }

  override func prepareLayout() {
    // some calculation i did for my cells
  }

  override func collectionViewContentSize() -> CGSize {
    return CGSize(width: contentWidth, height: contentHeight)
  }

  override func layoutAttributesForElementsInRect(rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
    var layoutAttributes = [UICollectionViewLayoutAttributes]()

    for attr in cache {
      if CGRectIntersectsRect(attr.frame, rect) {
        layoutAttributes.append(attr)
      }
    }
    return layoutAttributes
  }
}

了myCell

import UIKit

class MyCell : UICollectionViewCell {

  @IBOutlet weak var myLabel: UILabel!

}

Answer 1

尝试在ViewController类的viewDidLoad（）中删除此行：

self.gridView.registerClass(MyCell.self, forCellWithReuseIdentifier: reuseIdentifier)

由于您已在Storyboard中创建了UICollectionView，并且已连接到您的dataSource和delegate，并且您已添加了所有必需的方法，因此不需要它：

• numberOfItemsInSection
• cellForItemAtIndexPath